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Wisdom
Registered: Dec 2001
Posts: 90 |
Maximum number of sprites
Hello,
What is the maximum possible number of sprites on a PAL C64 at once?
There are a couple of numbers about this (based on 312 rasterlines);
1) 112 non-clipped sprites,
2) 112 non-clipped sprites + 8 clipped ones,
3) 144 sprites with 17 pixels height (Crossbow).
Which one would be of general acceptance as the maximum?
And, does the 3rd one really count, as it introduces another limit while trying to remove the other?
Is there any other 'legal' record around that I may not be aware of?
I would like to hear your comments. Thanks.
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Well, if you remove the upper and lower borders, and you take into account that once a sprite is beeing drawn, you can't change the y-pos of the sprite... It's a simple calculation of available rasterlines / minimal sprite height times eight, I guess...
So with,
$120 rasterlines
$15 sprite height
8 sprites per rasterline
it should be... 110 sprites...
Hmm, is this correct??? |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
3) 144 sprites with 17 pixels height (Crossbow).
How did crossbow do the new sprite height? My experience with sprites is, that once the VIC has started to draw the sprite, you can do whatever you want with the sprite's y-pos but nothing happens until the vic has finished drawing the sprite. After that you're free to move the sprite's y-pos again until the vic starts to draw it again...
So, if you want to draw more sprites, you have to be able to move the sprite's y-pos before the vic has finished drawing it.
How did he do this?
Is this done by fiddling with the vertical sprite expand ($d017)? |
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HCL
Registered: Feb 2003
Posts: 728 |
Hmm, how did you get 110!??! :). Guess you mean int($120 / $15) * 8, which is 104 sprites.
To get 144, look for "sprite crunching". It has been discussed on several threads already..
By the way, that 120-sprite record is just nonsence to me. Crossbow himself says that only whole sprites should be counted, so why suddenly bother to count clipped ones!?!? |
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Cruzer
Registered: Dec 2001
Posts: 1048 |
I think the 120 sprites record in "Ice Cream Castle" is pretty clever. AFAIK the sprites are not clipped, but they all move 3 pixels down each frame, so when a sprite is displayed, there is 312 + 3 rasterlines until it will be displayed again. And coincidently ((312 + 3)/21)*8 = 120. |
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HCL
Registered: Feb 2003
Posts: 728 |
It's more like a mathematical trick. Moving the sprites down makes them clipped, so they should not count according to master crossbow. Iterating 21 frames will of course result in showing each sprite 312 times. The only thing you can say about the amount of sprites on the screen it that each sprite is shown 14.857 times on average each frame. Not 120 in my world. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
all your clipped sprite are belong to us |
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HCL
Registered: Feb 2003
Posts: 728 |
Whata aapaned?
Someone setus uppa di sprite! |
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Mason
Registered: Dec 2001
Posts: 461 |
About the sprites I cant remember the exact words Hungry Hero wrote, but try to find Showcase Bonanza from Miracle and read his words.
Not sure if its any help, but he explains something about numbers and so. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
In case you also count the clipped sprites it's 128 sprites per frame and not 120. Or why do you only count the clipped sprites at the bottom and not the top? |
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Wisdom
Registered: Dec 2001
Posts: 90 |
I just wrongly termed it. Actually I was referring to that part in Ice Cream Castle, as Cruzer put.
So, the real question is; does that 144 sprites thing really count? (As in that case sprites are not full but crunched.) |
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